A fountain-like diarrhea emitting from one's anus.
Scott had a massive browntain that kept him on the jon for hours.
A mountain of human feces. Either in an urban environment or in nature. An uninterrupted pile with no indication of what was used to wipe.
Walking down Bourbon St. I encountered a browntain in the middle of the street. Miraculously it remained undisturbed as the crowds of people walked by.